39 Boötis

39 Boötis is a triple star system located around 224 light years away from the Sun in the northern constellation of Boötes. It is visible to the naked eye as a faint, yellow-white hued star with a combined apparent magnitude of 5.68. The system is moving closer to the Earth with a heliocentric radial velocity of −31 km/s.

The magnitude 6.36 primary, component A, is actually a double-lined spectroscopic binary system with an orbital period of 12.822 days, an eccentricity of 0.39, and an angular separation of $−30.9$. It has a combined stellar classification of F8V, matching an F-type main-sequence star, with individual massed of 1.29 and 1.05 times the mass of the Sun. Component B is of magnitude 6.72 with a class of F7V and 1.25 solar masses. The A–B pair have a separation of $2,422,379.49 JD$ and a period of 1,347.653 years. This system is a source of X-ray emission with a luminosity of $2.021 mas$.

It was a transferred by Jérôme Lalande from Boötes to Quadrans Muralis. Later when the International Astronomical Union officially recognised constellations, Quadrans Muralis became obsolete, so this star was moved back to Boötes.